Mitotic catastrophe, a cell death mechanism characterized by abnormal mitosis, has been regarded as a therapeutic approach for the development of anti‑cancer drug candidates. The aim of the present study was to investigate the potential effect of the ethanolic extract of Juniperus squamata (EEJS) on the occurrence of mitotic catastrophe in human oral cancer cell lines. The effect of EEJS on the occurrence of mitotic catastrophe was evaluated by measuring cytotoxicity, observing phase‑contrast or transmission electron microscope findings, evaluating the appearance of microtubule or chromosome abnormalities, and detecting the phosphorylation of histone H3 (Ser10). The apoptotic effect of EEJS was assessed by detecting cleaved PARP, analyzing the sub‑G1 population, Annexin V‑FITC/PI double staining, western blot analysis, and the transient transfection of myeloid cell leukemia‑1 (Mcl‑1) overexpression vectors. EEJS treatment was effective in inhibiting cell proliferation in human oral cancer cell lines. EEJS resulted in the enrichment of enlarged multinucleated cells, the disturbance of microtubule formation, and increased phosphorylation of histone H3 (Ser10), which demonstrates the occurrence of mitotic catastrophe. Additionally, the multinucleated cells underwent apoptotic cell death in a cell context‑dependent manner, which was associated with the reduction of Mcl‑1 protein levels. Findings of the present study indicate that EEJS could be effective for treating human oral cancer by promoting mitotic catastrophe linked to apoptotic cell death.
Keywords: Juniperus squamata; Mcl‑1; apoptosis; mitotic catastrophe; oral cancer; phospho‑Histone H3.